In the field of fabrication and molding of glass articles and products a molding station is known to use special molds composed of multiple parts, which are adapted to receive a glass gob in a plastic or molten state for molding the article.
Particularly, the gob is deposited on a part of the mold, known as die, which usually defines the outer shape of the article or glass container to be molded.
The mold also comprises a second part, known as plunger, which defines the inner shape of the article or glass container to be molded, wherein during molding such second part or plunger closes against the die containing the gob, to cause expansion thereof in the gap formed by the die and the plunger.
Also the mold may comprise one or more additional parts that are designed to close against one another in combination with the die and the plunger, to close and completely seal the mold, such that the inner cavity of the mold will assume a shape that exactly matches the shape of the glass article to be molded.
Therefore, when the mold is closed, the glass gob that was initially deposited in the die is pressed and expands to entirely fill the mold cavity and form the article.
Of course, the shape and mutual arrangement of the various parts of the mold will change according to the particular configuration and exterior appearance of the glass article to be molded.
In short, these parts of the mold are designed and controlled to close upon one another, as mentioned above, to close the mold and form the article, and later separate from one another to allow removal of the molded glass article from the mold.
The die that defines the outer shape of the glass article to be molded is usually composed of two mating parts that close upon each other to form the inner cavity of the mold and separate from each other, once the glass article has been molded, to allow removal of the glass article.
For better clarity, FIG. 9 schematically shows the structure and basic parts of a typical conventional mold, referenced ST, which is used in a molding station SS, to mold a glass article AV, e.g. consisting of a container such as a salad bowl or the like.
Particularly, this conventional mold ST is essentially composed of a plurality of distinct and mutually separable parts or pieces, referenced P1, P2, P3, P4.
More in detail, the pieces P1 and P2 compose the die of the mold ST, also designated as MAT, and form a concave surface SUP′ in their mutually closed state, which corresponds with and defines the outer shape of the glass article AV, to be molded.
The piece P3, i.e. the plunger, defines in turn a convex surface SUP″ which corresponds to and defines the inner shape of the glass article AV, to form a gap with the concave surface SUP′ of the die MAT, when the plunger P3 is closed thereupon, said gap corresponding to the wall of the article AV to be molded and setting its thickness.
Finally, the piece P4 has a general ring shape, and is designed to close upon the die MAT to laterally close the gap between the plunger, i.e. the piece P3 and the die MAT of the mold ST, and form the inner cavity of the mold ST with the other pieces.
When the glass article AV is molded using this conventional mold ST, the two pieces P1 and P2 are closed against each other to form the die MAT, as shown by arrows f.
Then, as shown in section (a) of FIG. 9, a glass gob V in a plastic or molten state is deposited into the die MAT formed by the pieces P1 and P2.
Later, the upper part P3, i.e. the plunger, is closed with the ring-shaped piece P4 upon the die MAT formed by the pieces P1 and P2, as shown by arrows f′ and in section (b) of FIG. 9, to press the glass gob V and cause deformation and expansion thereof in the gap between the die MAT and the plunger P3, to fill the whole inner cavity of the mold ST, thereby forming the glass article AV.
Finally, the parts of the mold ST are moved apart from each other, as shown by arrows f″ and in section (c) of FIG. 9, for removal of the glass article AV from the mold ST.
A need is also known to arise in the field of glassware fabrication and molding, for the possibility of manufacturing and fabricating glass articles with a configuration characterized by one or more through holes, and apertures in general, formed through their walls.
This need has been generally addressed, in the prior art, by the design and construction of special molds whose parts are configured and appropriately controlled to define these holes and these apertures during molding and formation of the glass article.
Nevertheless, the molds and molding equipment that are currently available in the prior art for molding glass articles having one or more through holes are at least generally found to have a rather complex and complicated construction.
Furthermore, these prior art molds usually comprise dies composed of two or more mutually separable parts, which involves a rather complex operation, particularly for displacement of these parts, with adverse effects on both mold fabrication and molding costs, as well as on the final cost of the finished bored glass article.
Embodiments of molds for glass articles, such as containers or glasses, are also known, which have a through hole or aperture formed through their walls, wherein the hole is formed, during molding, by a moving element in the area of the gap between the die and the plunger.
Particularly, during molding of the article, this element is placed in such position as to extend through the gap between the die and the plunger of the mold, to define a gap area corresponding to the through aperture or hole to be formed in the article, which does not receive or is not filled with the molten glass.
Then, this element is withdrawn from the gap, once the glass has solidified, to clear the hole and allow both die and plunger separation and removal of the bored glass article from the mold.
Nevertheless, this solution is also complex, in terms of both construction and operation, and still has drawbacks.